Author's Preface to the Reader, First Edition

Since the ancients (according to Pappus) considered mechanics to be of the greatest importance in the investigation of nature and science and since the moderns – rejecting substantial forms and occult qualities – have undertaken to reduce the phenomena of nature to mathematical laws, it has seemed best in this treatise to concentrate on mathematics as it relates to natural philosophy. The ancients divided mechanics into two parts: the rational, which proceeds rigorously through demonstrations, and the practical. Practical mechanics is the subject that comprises all the manual arts, from which the subject of mechanics as a whole has adopted its name. But since those who practice an art do not generally work with a high degree of exactness, the whole subject of mechanics is distinguished from geometry by the attribution of exactness to geometry and of anything less than exactness to mechanics. Yet the errors do not come from the art but from those who practice the art. Anyone who works with less exactness is a more imperfect mechanic, and if anyone could work with the greatest exactness, he would be the most perfect mechanic of all. For the description of straight lines and circles, which is the foundation of geometry, appertains to mechanics. Geometry does not teach how to describe these straight lines and circles, but postulates such a description.

LETTER ONE

Cambridge, 10 December 1692

To the Reverend Dr Richard Bentley, at the Bishop of Worcester's House in Parkstreet, Westminster.

SIR,

WHEN I wrote my treatise about our system, I had an eye upon such principles as might work with considering men, for the belief of a deity, and nothing can rejoice me more than to find it useful for that purpose. But if I have done the public any service this way, it is due to nothing but industry and patient thought.

As to your first query, it seems to me that if the matter of our sun and planets, and all the matter of the universe, were evenly scattered throughout all the heavens, and every particle had an innate gravity towards all the rest, and the whole space, throughout which this matter was scattered, was but finite; the matter on the outside of this space would by its gravity tend towards all the matter on the inside, and by consequence fall down into the middle of the whole space, and there compose one great spherical mass. But if the matter was evenly dispersed throughout an infinite space, it would never convene into one mass, but some of it would convene into one mass and some into another, so as to make an infinite number of great masses, scattered at great distances from one to another throughout all that infinite space. And thus might the sun and fixed stars be formed, supposing the matter were of a lucid nature.

LEIBNIZ TO NEWTON

Hanover, 7 March 1692/3

To the celebrated Isaac Newton: Gottfried Wilhelm Leibniz sends cordial greetings

How great I think the debt owed to you, by our knowledge of mathematics and of all nature, I have acknowledged in public also when occasion offered. You had given an astonishing development to geometry by your series; but when you published your work, the Principia, you showed that even what is not subject to the received analysis is an open book to you. I too have tried by the application of convenient symbols, which exhibit differences and sums, to submit that geometry which I call “transcendent” in some sense to analysis, and the attempt did not go badly … [.]

But above all I would wish that, perfected in geometrical problems, you would continue, as you have begun, to handle nature in mathematical terms; and in this field you have by yourself with very few companions gained an immense return for your labor. You have made the astonishing discovery that Kepler's ellipses result simply from the conception of attraction or gravitation and passage in a planet. And yet I would incline to believe that all these are caused or regulated by the motion of a fluid medium, on the analogy of gravity and magnetism as we know it here. Yet this solution would not at all detract from the value and truth of your discovery.

NEWTON TO COTES

London, 28 March 1713

Sir

I had your [letter] of Feb 18th, and the difficulty you mention which lies in these words “And since, by the third law of motion, every attraction is mutual” is removed by considering that as in geometry the word “hypothesis” is not taken in so large a sense as to include the axioms and postulates, so in experimental philosophy it is not to be taken in so large a sense as to include the first principles or axioms which I call the laws of motion. These principles are deduced from phenomena and made general by induction: which is the highest evidence that a proposition can have in this philosophy. And the word “hypothesis” is here used by me to signify only such a proposition as is not a phenomenon nor deduced from any phenomena but assumed or supposed without any experimental proof. Now the mutual and mutually equal attraction of bodies is a branch of the third law of motion and how this branch is deduced from phenomena you may see in the end of the corollaries of the laws of motion, page 22. If a body attracts another body contiguous to it and is not mutually attracted by the other: the attracted body will drive the other before it and both will go away together with an accelerated motion in infinitum, as it were by a self-moving principle, contrary to the first law of motion, whereas there is no such phenomenon in all nature.

NEWTON TO BOYLE

Cambridge, 28 February 1678/9

Honoured Sir,

I have so long deferred to send you my thoughts about the physical qualities we spoke of, that did I not esteem myself obliged by promise, I think I should be ashamed to send them at all. The truth is, my notions about things of this kind are so indigested, that I am not well satisfied myself in them; and what I am not satisfied in, I can scarce esteem fit to be communicated to others; especially in natural philosophy, where there is no end of fancying. But because I am indebted to you, and yesterday met with a friend, Mr. Maulyverer, who told me he was going to London, and intended to give you the trouble of a visit, I could not forbear to take the opportunity of conveying this to you by him.

1. It being only an explication of qualities, which you desire of me, I shall set down my apprehensions in the form of suppositions, as follows. And first, I suppose, that there is diffused through all places an aethereal substance, capable of contraction and dilatation [i.e. dilation], strongly elastic, and in a word much like air in all respects, but far more subtle.

2. I suppose this aether pervades all gross bodies, but yet so as to land rarer in their pores than in free spaces, and so much the rarer, as their pores are less.

It is fitting to treat the science of the weight and of the equilibrium of fluids and solids in fluids by a twofold method. To the extent that it appertains to the mathematical sciences, it is reasonable that I largely abstract it from physical considerations. And for this reason I have undertaken to demonstrate its individual propositions from abstract principles, sufficiently well known to the student, strictly and geometrically. Since this doctrine may be judged to be somewhat akin to natural philosophy, in so far as it may be applied to making clear many of the phenomena of natural philosophy and in order, moreover, that its usefulness may be particularly apparent and the certainty of its principles perhaps confirmed, I shall not be reluctant to illustrate the propositions abundantly from experiments as well, in such a way, however, that this freer method of discussion, disposed in scholia, may not be confused with the former, which is treated in lemmas, propositions and corollaries.

The foundations from which this science may be demonstrated are either definitions of certain words, or axioms and postulates no one denies. And of these I treat directly.

Definitions

The terms ‘quantity’, ‘duration’, and ‘space’ are too well known to be susceptible of definition by other words.

Query 28

[…] And against filling the heavens with fluid mediums, unless they be exceeding rare, a great objection arises from the regular and very lasting motions of the planets and comets in all manner of courses through the heavens. For thence it is manifest, that the heavens are void of all sensible resistance, and by consequence of all sensible matter.

For the resisting power of fluid mediums arises partly from the attrition of the parts of the medium, and partly from the vis inertiae [force of inertia] of the matter. That part of the resistance of a spherical body which arises from the attrition of the parts of the medium is very nearly as the diameter, or at the most, as the factum [factor] of the diameter, and the velocity of the spherical body together. And that part of the resistance which arises from the vis inertiae of the matter, is as the square of that factum. And by this difference the two sorts of resistance may be distinguished from one another in any medium; and these being distinguished, it will be found that almost all the resistance of bodies of a competent magnitude moving in air, water, quicksilver, and such like fluids with a competent velocity, arises from the vis inertiae of the parts of the fluid.

Interpreting Darwin

Prior to the twentieth century, no prominent scientist has left so detailed a record of his life and thought as has Charles Darwin. Between notebooks, marginalia, unpublished as well as published works, and a vast correspondence, he has provided an almost endless set of data for scholars to assimilate and interpret. Traditionally, most students of Darwin followed what Hodge has called the “Franciscan” view – that is, a view supported by his life and letters as Darwin's son Francis assembled and published them (Hodge 1985, p. 207), and also by the brief autobiography Darwin himself wrote for the benefit of his family (Darwin 1958). Since then, a great deal of further material has entered the public domain: Darwin's sketch of his theory in 1842 and his essay of 1844, the unfinished draft of his “big book,” Natural Selection, the transmutation notebooks, and a more complete correspondence, carefully annotated, now available through the year 1863 (as of the present writing). Darwin scholars, members of the “Darwin industry,” also delve into other material still tucked away in the Darwin archives of the Cambridge University library. Further, as available material by Darwin continues to increase in volume, so, inevitably, do commentaries on it. In this situation, it is difficult to step backward and consider briefly Darwin's stance and his impact in some of the areas we are concerned with.

Introduction

The evolution of human beings, and the meaning of “human nature” within a comparative, biologically grounded framework of inquiry, is a huge topic, extending well beyond the contours of this book. Nonetheless, much of the interest that human beings have in other living beings reflects our unquenchable interest in ourselves. In this chapter, accordingly, we will say a few things about several aspects of human evolution, if only by way of commending further inquiry to the reader. We will touch, first, on human origins – “the descent of man,” in Darwin's phrase – with particular attention to the unity of the human species; second, on the vexed topic of nature and nurture; third, on the evolutionary mechanisms required to account for characteristics that human beings alone possess: large brains, language, and mind; and finally, we will touch on what implications, if any, can be drawn about the “future of man” from the Human Genome Project, and, more generally, from the fact that within the last several decades, we have begun to acquire the technical ability directly to manipulate genetic material. Much of what we will have to say involves revisiting some of the figures and theories we have encountered earlier in this book, with special attention this time to our own species.

The Descent of Man

Buffon is generally accorded the title of “father of anthropology.” In his Histoire naturelle de l'homme (1749), Buffon resolved to study human beings in the same way he had been studying other animals.

There would never be, Immanuel Kant assured his readers, a “Newton of a blade of grass.” Living things, he believed, are examples of “natural purposes,” entities organized so purposefully that we cannot explain them altogether through the blind causality we apply to inanimate nature. At the same time, Kant argues that if living beings are organized purposely, or on purpose, rather than just purposefully, we cannot know it. There seems to be something special about things that are alive that exempts them from Newtonian mastery.

Something like this, although not quite in Kantian terms, has been the view of many natural historians, physicians, and comparative anatomists, as well as philosophers, in our tradition. Others, notably Descartes and his followers, as well as more recent “reductionist” thinkers, have denied that any such difference exists.

Yet even among those who stress the uniqueness of life, a number have appeared, at least implicitly, to welcome the accolade of “Newton of a blade of grass,” whether for themselves or others. Georges Cuvier seems to have been happy to assume that title, though it was animals, not plants, that he studied. But he would also have been willing to claim the crown for Master Aristotle. Some thought Cuvier's rival, Etienne Geoffroy Saint-Hilaire, more worthy of that honor. And of course many have since found that it was Charles Darwin who gave the study of life such a new and scientifically satisfying solution that he truly deserved the title “Newton of a blade of grass.”

What Is the Modern Evolutionary Synthesis?

The Modern Evolutionary Synthesis has served as the dominant interpretive framework that has guided professional evolutionary biology during the central decades of the twentieth century. Just what was being synthesized? In the 1920s and 1930s, there occurred a synthesis between Mendelian genetics and Darwinism, whose champions had earlier been at each others' throats (see Chapter 8). The central figures in this effort were R. A. Fisher, J. B. S. Haldane, and Sewall Wright. However, the phrase “modern evolutionary synthesis” refers not only to the synthesis between Mendelism and Darwinism, but to a sustained effort extending from the late 1930s through the 1940s to use “population genetics,” in the sense worked out by these pioneers, to unify – synthesize – a wide array of biological disciplines. That is how Julian Huxley, grandson of Thomas Huxley, used the phrase in his 1942 book Evolution: The Modern Synthesis, which gave the Synthesis its name. Huxley listed “ecology, genetics, paleontology, geographical distribution [biogeography], embryology, systematics, [and] comparative anatomy” as “converging upon a Darwinian center,” thereby rescuing Darwinism from its turn-of-the century “eclipse” (Huxley's phrase) and, in Huxley's opinion, bringing into being for the first time a truly modern, theoretically based, biology (Huxley 1942; 1943, p. 25). Key figures in the Modern Synthesis in Huxley's sense were Theodosius Dobzhansky, Ernst Mayr, George Gaylord Simpson, and G. Ledyard Stebbins. All these figures wrote books in a series published by Columbia University Press between 1937 and 1952.

In concluding our retrospective of the relations between philosophy and biology past and present, we may ask what the emergence of a philosophy of biology can contribute to the philosophy of science in general. What can the study of biology teach us if we take it either as our model field or as a model for our field?

There have so far been two major movements in recent philosophy of science. First, there was the so-called received view, initially logical positivism, rechristened logical empiricism. Taking fundamental physics, or a caricature of it, as its model, it separated the process of discovery (which it ignored) from the context of justification. Within the latter context, it aimed at a logical reconstruction of science, a science that rigorously followed a single hypothetico-deductive method, and that was to issue in the utopian structure of a unified science. In reaction, sociologists, and even some philosophers of science, have practiced a sociological deconstruction of science, which has left that family of disciplines with no claim whatsoever to epistemic justification. For the first school, science, with its sacrosanct method, stands serenely outside society, or else deigns to direct it by applying its superior procedure. For the second, science is reduced to politics: In effect, there is only society, no science.

What if we come to the philosophy of science through reflections on biology rather than physics, or some abstract dream of physics, as the received view used to do, or in preference to taking as our model for philosophy a rather naive sociology?

Introduction

Aristotle is the one philosopher in our history who is also a great biologist, and, indeed, whose metaphysic, as we have come to call it, serves as grounds for his biological interests. But even in ancient times, as we have seen, his life-centered philosophy was modified in favor of a more mechanistic perspective. Here we will be looking at the seventeenth-century confrontation of the Aristotelian tradition with more mechanistic views, especially in Descartes. In England at least, Gassendi, one of the most outspokenly critical Objectors to the Meditations, was perhaps as influential as Descartes. However, we are not attempting a survey here; and Descartes can certainly be taken as one of the chief proponents of the new mechanism in biology.

Like many such labels, “mechanism” is a term imposed by critics and historians. Moreover, it is an ambiguous term. In connection with the sense of “Mechanics” introduced apologetically by Robert Boyle in the late seventeenth century, mechanism suggests billiard-ball causality, just one thing after another (see O.E.D. entry under “Mechanics”). In an earlier meaning, which still resonates in the notion of mechanistic biology, mechanism is concerned with machines. Thus, for example, when Huygens asked Descartes for some examples of mechanics, Descartes sent him accounts of several “engines by means of which one can lift a very heavy weight with a small lever” – we might say, several mechanisms (Descartes 1637; AT I, pp. 395, 435).

Introduction

In the main, it was only in the second half of the twentieth century that the philosophy of biology emerged as a distinctive sub-discipline in academic philosophy. Indeed, the philosophy of science as such – as distinct from “natural philosophy” or just philosophy – is a relatively recent phenomenon. At its start, however, with the rise of logical positivism, soon renamed logical empiricism, it was chiefly a philosophy focused on physics, or even, in its extreme reconstructionist forms, a philosophy based on a rather slanted view, even a caricature, of that “fundamental” science. The life sciences were usually ignored, or treated as an embarrassment to be explained away. True, J. H. Woodger produced in the nineteen-thirties what was supposed to be a statement of the principles of biology; but apart from a few followers in Great Britain, his effort had little influence (Woodger 1937). In general, the hope of philosophers of science was that all the sciences would one day (perhaps even soon?) be unified in the terms of, and through the theories of, the most basic level of physics. For example, at one of C. H. Waddington's conferences on theoretical biology, there was one very vocal participant who kept deploring that the Volterra–Lotka equations, which express regularities in populations, could not (yet?) be reduced to terms of quantum mechanics. Nothing else was really science.